DMK President Karunanidhi said in a statement that his party never interfered in Centre's foreign policy or its internal affairs "and in the same way we don't accept DMK interfering in the visa issue."

"While MPs have denied they have signed the letter, the party does not accept them signing it. Sending a signed note is not acceptable to the party. If any of our MPs had signed the letter without discussing the matter with the high command, party will take action against them," he said in a statement.

The 90 year-old Karunanidhi's warning came a day after a controversy erupted over a letter purportedly signed by a set of MPs including Sitaram Yechury (CPI-M) and DMK's KP Ramalingam to Obama asking that Modi be not granted US visa, which both have denied.

Quoting reports in this regard, Karunanidhi said his party MPs had told him that they had not signed the petition.

BJP has accused the Congress' "dirty tricks department" of being behind it and demanded a probe. Congress had also denied any role for it on this issue.